1. Field of the Invention.
This invention pertains to scraped surface heat exchangers.
2. Description of the Prior Art.
A conventional dual scraped surface heat exchanger utilizes inner and outer heat transfer surfaces to maintain a desired surface to volume ratio by suitable selection of the inner and outer diameters. In a single surface heat exchanger, the surface to volume ratio would decrease with an increase in diameter. With two surfaces involved, scraping both surfaces with a single spiral rib or flight, which would also convey the material through the heat exchanger, presents a difficult manufacturing problem due to the clearances encountered. Further, the single rib would positively advance the material and could damage the fragile, discrete particles therein as a resistance is encountered such as adjacent a discharge.